1. Field of the Invention
This disclosure relates to a power-saving technique for a discontinuous reception mechanism in a wireless communication system, and, more particularly, to a data scheduling system and a method thereof that satisfy quality of service (QoS) and minimize power consumption.
2. Description of Related Art
Long term evolution (LTE) is becoming the most promising communication technology, which has a high transmission rate and high coverage, but consumes more power. Moreover, LTE defines a discontinuous reception (DRX) power-saving mechanism. The DRX power-saving mechanism may turn off radio-frequency circuits periodically, in order to achieve the power-saving effect. However, packets may not be received when turning off the radio-frequency circuits, such that quality of service (QoS) will be affected.
Since a wireless network has variable channel conditions, different DRX parameters are required under different channel conditions in order to achieve a high transmission rate. However, the DRX parameters are determined without considering the channel conditions of users. Therefore, it is necessary to solve the channel adaptation problem by dynamically adjusting DRX parameters. Additionally, traffic and QoS of network services are not considered in the manner of DRX parameters. For example, a single user may simultaneously request a plurality of network services. Each of network services may have different traffic pattern and QoS requirements. In order to satisfy QoS for all the network services, it is necessary to acquire a set of optimal DRX parameters for transmission of wireless networks.
Moreover, if on periods that radio-frequency circuits are turned on by users are not distributed evenly, the users may turn on their radio-frequency circuits simultaneously and share the network resource, such that transmission or reception of data may not be completed and power consumption may also be increased. Therefore, it is also necessary to obtain a proper DRX start offset in order to uniformly disperse the on durations of the network devices and improve the transmission efficiency as well as the power saving. Most commonly, the DRX start offset parameters of all the users have to be re-determined while an additional user requests for the network services. Such a mechanism cannot change the DRX parameters only for the additional user, such that the system load caused by signaling may be increased.
Further, DRX inactivity timer will be reset if a user is scheduled. With this feature, a user that will go for sleep at the next subframe is scheduled to extend the inactivity timer if the packets of the user are not transmitted completely. However, frequently extending the on duration will significantly increase power consumption especially in the case of poor channel condition or high system load. The reason is that the system may not have sufficient radio resources to allocate to the user in its extended on duration.
Therefore, for the sake of meeting the requirements of the system load, it is necessary to provide a method for acquiring the optimal DRX parameters for LTE so as to satisfy QoS requirements and consume less power.
Accordingly, solutions to the problems described above have been long sought, but prior developments have not taught or suggested any solutions and, thus, solutions to the problems have long eluded those skilled in the art. Therefore, there is a heretofore-unaddressed need to overcome defects and shortcomings described above.